Control valve for positive crankcase ventilation system

ABSTRACT

A control valve for a positive crankcase ventilation system of an internal combustion engine. The valve includes a pressure differential decay means which retards valve modulation during accelerations from low speeds, thereby minimizing the leaning effect that the positive crankcase ventilation system otherwise would have on the combustible mixture.

United States Patent Marlett [54] CONTROL VALVE FOR POSITIVE CRANKCASE VENTILATION SYSTEM [72] Inventor: N. William Marlett, Dearborn Heights,

Mich.

[73] Assignee: Ford Motor Company, Dearbom, Mich.

[221 Filed: March 31, 1971 21 Appl. No.: 129,833

[151 3,678,910 51 July 25,1972

3,308,798 3/1967 Snider ..l23/ll9B 175,035 3/1876 Conaughton ..25l/55 Primary Examiner-Wendell E. Burns Assistant Examiner-A. M. Zupcic Attorney-John R. Faulkner and Roger E. Erickson ABSTRACT A control valve for a positive crankcase ventilation system of an internal combustionengine. The valve includes'a pressure [52] US. Cl... ..l23/1 19 B 137/480 511 Int. Cl ....F02t 9/00, F62n 25/06 f if f 'l wh'ch I 3 f f f' 5s Fleldolsearch ..123/119 B, 124 R; 251/55; W m y 9 9 137/479 480 anmg effect that the positive crankcase ventilation system otherwise would have on the combustible mixture.

[561 6Clalms, 5 Drawing figures UNITED STATES PATENTS 2,884,950 5/l959 Settelmayer et al ..l23/119 B j] if 41 47,!4 4! ll is! 3 J7 11 ,4 y 4 if V 4/ if 1/ Patented July 25, 1972 3,678,910

' 2 Sheets-Sheet 2 M m/z/z/vrv/a. Q N. WILL MM MAACLETT u 2. Hum gqanjlftmmk) CONTROL VALVE FOR POSITIVE CRANKCASE VENTILATION SYSTEM BACKGROUND OF THE INVENTION The crankcase, valve chamber and timing gear housing of an automotive internal combustion engine are generally vented in order to prevent condensation, acid formation, damage from corrosive fumes and sludge deposits. Nearly all engines produced in recent years have employed ventilation systems of the type comprising a hose or tube extending from the crankcase or valve chamber to the intake manifold or air cleaner. Such systems are commonly called positive crankcase ventilation systems. When a hose or tube to the intake manifold is used, a valve controls the air flow so as to restrict the circulation at idle operation and to open the system at higher engine speeds. The valve restriction or opening generally is a function of the pressure differential between the crankcase or valve chamber and the intake manifold. It is desirable to reduce air flow to the intake manifold during low engine speeds and during certain transient conditions to prevent excessive leaning of the combustiblemixture which can result in engine stumble or stall if not otherwise compensated. An unrestricted ventilating air flow at low speeds can result also in erratic or inconsistent low speed fuel-air ratios.

This invention provides a positive crankcase ventilation system control valve that restricts air flow through the ventilating system into the intake manifold and prevents excessive leaning of the combustible mixture during accelerations from low speeds, as well as during steady idle or low speed operations.

Furthermore, this invention provides a ventilation control valve which operates both as a function of time and a function of pressure differential. The invention also provides a means by which the opening of the valve is delayed during transient acceleration conditions in which the intake manifold vacuum pressures decrease suddenly.

SUMMARY OF THE INVENTION An internal combustion engine having a ventilated crankcase and an intake manifold, constructed in accordance with this invention, includes a passage communicating the interior of the crankcase with the interior of the intake manifold. Valve means are positioned within the passage to open and close the passage in response to the pressure differential between the intake manifold and the atmosphere. The valve includes a pressure differential decay means to retard the opening response of the valve upon a sudden decrease in intake manifold vacuum pressure such as is experienced upon rapid acceleration from low engine speeds.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I of the drawings is a cross-sectional view of a positive crankcase ventilation valve constructed in accordance with this invention.

FIG. 2 is a view with portions broken away taken along line 2-2 of FIG. 1.

FIG. 3 is a schematic view of the positive crankcase ventilation valve showing its connection with a typical V-8 internal combustion engine.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT A typical V-8 internal combustion engine 11 is shown in FIG. 3 of the drawings in which the flow of a positive crankcase ventilation system is represented schematically by a series of broken lines and arrows. The ventilating air is initially drawn from the air cleaner 12 through hose 13 to the interior of valve cover 14. The ventilating air is then drawn from the valve cover through ventilating passages within the engine block (not shown) to the crankcase 16 and the timing gear enclosure (not shown) and, finally, into the opposite valve cover 17. The ventilating air, along with the oil fumes that it has picked up, is then drawn from the interior of valve 17 through line 15 to the positive crankcase ventilation valve assembly 18 which regulates its flow rate. After having passed through the valve assembly, the air and fumes are drawn through line 20 into the intake manifold 19 through a fitting 21 positioned in the carburetor spacer 22. The ventilating air and the oil fumes drawn into the intake manifold are combined with the fuel-air mixtures from the carburetor and form a part of the combustible mixture transmitted to the individual engine cylinders (not shown).

The valve assembly 18 comprises a vacuum motor portion 23 and a flow control portion 24. The flow control portion includes a housing 26 having inlet and outlet fittings 27and 28. respectively, an orifice 29 and a tapered metering plunger 31 received within the orifice and axially and movable into and out of the orifice to increase and decrease the efiective orifice opening.

The upper portion 23 of the valve assembly 18 defines a vacuum motor enclosure 32 divided into two variable volume compartments 33 and 34 by a rubber diaphragm 36. The lower side of the diaphragm or compartment 34 is subjected continuously to atmospheric pressure which enters the compartment through vent 37. The upper side of the diaphragm or compartment 33 is exposed to intake manifold vacuum. A line 38 is connected to fitting 39 on the upper end of the valve assembly and together with line 20 communicates the upper compartment 33 of the vacuum motor with the intake manifold 19.

Rod 41 interconnects the vacuum motor diaphragm 36 and the plunger 31 to transmit the motions of the diaphragm to the plunger and vary the effective opening or the restriction of orifice 29. Rod guide 42 maintains the radial position of the plunger rod and seal 43 separates the atmospheric pressure of the lower compartment 34 from the vacuum pressure of the ventilating air flow within housing 26. Compression spring 44 acts against the housing and the diaphragm fitting 46 to urge the rod 41 and plunger 31 downwardly into a less restricting position within orifice 29. The atmospheric pressure or the pressure differential acting on the diaphragm 36 opposes the force of the compression spring 44 to urge the plunger 31 toward a more restrictive position.

A time delay check valve assembly 47 includes an enclosure 48 having upper and lower seating surfaces 49 and 51 with openings 52 and 53, respectively, which form part of the passage or communication means from the upper compartment 33 of the vacuum motor to the intake manifold 19. A movable element 54 received within the enclosure 48 has generally a crown shape. When the movable element is seated on the upper surface 49, the vacuum pressure is communicated between the fingers 56 of the crown and through openings 52 and 53 with relatively unrestricted flow. When the movable element 54 is seated on the lower surface 51 of the enclosure, the communication between the upper compartment of the vacuum motor and the intake manifold must pass through the restricting orifice 57 of the movable element 54. It may be seen that if the differential between the intake manifold vacuum pressure and atmospheric pressure decreases suddenly, then the flow into compartment 33 will seat the movable element 54 on lower surface 51 and the pressure differential between the upper compartment of the vacuum motor and the intake manifold will equalize itself over a predetermined period of time through the restricted orifice 57.

OPERATION The basic function of the pressure differential responsive valve 18 within a positive crankcase ventilation system as shown in FIG. 3 of the drawings, is to restrict the flow of ventilating air during low and idle engine speeds. Unrestricted flow of ventilating air during these engine speeds has a leaning or dilution efiect on the combustible mixture resulting in stumble or stall and potentially erratic or inconsistent fuel-air ratios. Thus, when the engine is idling and the intake manifold vacuum is correspondingly high, the positive crankcase ventilation valve causes restricted flow through the lines and which reduces the dilution effect of the ventilating air entering the combustible mixture. As the engine speeds are increased and the air flow through the carburetor spacer and the intake manifold is correspondingly increased, the valve 18 decreases its restriction and permits full flow of ventilating air so as to achieve complete crankcase ventilation at speeds at which the dilution effect of the ventilation air and gases entering the combustible mixture is negligible. This invention includes a time delay means 47 within the valve assembly 18 so that when the intake manifold vacuum drops suddenly as a result of a rapid acceleration from a low enging speed the valve plunger 31 will not immediately flow of crankcase ventilation air through orifice 29 will be delayed during the period of acceleration.

More particularly, sudden acceleration from a low speed decreases the intake manifold vacuum causing the movable check valve element 54 to seat on the lower surface 51 of the enclosure because the absolute air pressure within the upper compartment 33 of the vacuum motor becomes less than that in the intake manifold 19. The intake manifold 199 pressure and the upper compartment 33 pressure equalize over a period of time by air bleeding through the orifice 57 of the movable check valve element. It can be seen that the size of the orifice within the movable check valve element determines the period of time in which the pressures equalize and in which the plunger 31 reaches its minimum restriction position.

Control of the flow of crankcase ventilating air during accelerations from low speed as described above permits under certain circumstances, a reduction in other enrichment techniques or devices that can, in order to provide a rich enough mixture to prevent engine stumble, result in dirty exhaust emission characteristics.

1 claim:

1. in an internal combustion engine having a ventilated crankcase and an intake manifold,

passage means communicating the crankcase and the intake manifold,

valve means providing a variable restriction within said passage means in response to intake manifold vacuum pressure,

and means to urge said valve meanS to urge said valve means in a given direction and means to delay the response of said valve means upon a sudden change in intake manifold vacuum pressure.

2. The apparatus of claim 1,

said delay means comprising pressure differential decay means.

3. The apparatus of claim 2,

said valve meanS including a vacuum motor in communication with said intake manifold,

said pressure differential decay means restricting the communication between said vacuum motor in one flow direction and permitting relatively unrestricted communication between said vacuum motor in the opposite flow direction.

4. The apparatus of claim 2,

said valve means including an orifice formed within said passage means and a tapered plunger movable within said orifice to vary the effective restriction thereof.

5. The apparatus of claim 3,

said valve means including an orifice formed within said passage means and a tapered plunger movable within said orifice to vary the effective restriction thereof, and

said valve means including an orifice formed within said passage means and a tapered plunger movable within said orifice to vary the effective restriction thereof, and

means connecting the vacuum motor and the plunger for coordinated movement.

6. In, an internal combustion engine having a ventilated crankcase and an intake manifold,

passage means communicating the crankcase and the intake manifold and permitting flow from the crankcase to the manifold,

valve means providing a variable restriction within said passage,

said valve means including a housing forming a portion of said passage means,

an orifice positioned within said housing,

tapered plunger means movable into and out of said orifice to variably restrict and regulate flow through said orifice,

a chamber sealed from said housing being in communication with the intake manifold,

a flexible diaphragm dividing said chamber into two separate variable volume compartments,

connecting means transmitting motion of said diaphragm to said plunger means,

a first of said compartments being vented to the atmosphere,

passage means communicating the second of said compartments with the intake manifold,

spring means urging said plunger into a minimum restriction position and said second compartment to maximum volume,

check valve means permitting relatively unrestricted collapse of said second compartment and closing of said first-mentioned valve means in response to a decrease in pressure differential between the intake manifold and the atmosphere,

said check valve means having a pressure decay means permitting a controlled and restricted expansion of said second compartment over a predetermined period in response to an increase in pressure differential between the intake manifold and the atmosphere.

, UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. .v-'3, 7 ,9 Dated ly 25, 1972 William Marlett a Inventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 3-, line 45, delete entirely;

line :6, delete f'means" and substitute means line 5 1, delete "means" and substitute mean-s sighed and sealed this 11th day of February 1975.

(SEAL) Attest:

' f C. MARSHALL DANN RUTH C. MASON Commissioner of Patents Attesting Officer and Trademarks .USCOMM-DC 60376-P69 c u.s. GOYEPNMENT PRINTING orncs; I969 o-aes-aaa FORM PO-IOSO 10-69) 

1. In an internal combustion engine having a ventilated crankcase and an intake manifold, passage means communicating the crankcase and the intake manifold, valve means providing a variable restriction within said passage means in response to intake manifold vacuum pressure, and means to urge said valve meanS to urge said valve means in a given direction and means to delay the response of said valve means upon a sudden change in intake manifold vacuum pressure.
 2. The apparatus of claim 1, said delay means comprising pressure differential decay means.
 3. The apparatus of claim 2, said valve meanS including a vacuum motor in communication with said intake manifold, said pressure differential decay means restricting the communication between said vacuum motor in one flow direction and permitting relatively unrestricted communication between said vacuum motor in the opposite flow direction.
 4. The apparatus of claim 2, said valve means including an orifice formed within said passage means and a tapered plunger movable within said orifice to vary the effective restriction thereof.
 5. The apparatus of claim 3, said valve means including an orifice formed within said passage means and a tapered plunger movable within said orifice to vary the effective restriction thereof, and said valve means including an orifice formed within said passage means and a tapered plunger moVable within said orifice to vary the effective restriction thereof, and means connecting the vacuum motor and the plunger for coordinated movement.
 6. In an internal combustion engine having a ventilated crankcase and an intake manifold, passage means communicating the crankcase and the intake manifold and permitting flow from the crankcase to the manifold, valve means providing a variable restriction within said passage, said valve means including a housing forming a portion of said passage means, an orifice positioned within said housing, tapered plunger means movable into and out of said orifice to variably restrict and regulate flow through said orifice, a chamber sealed from said housing being in communication with the intake manifold, a flexible diaphragm dividing said chamber into two separate variable volume compartments, connecting means transmitting motion of said diaphragm to said plunger means, a first of said compartments being vented to the atmosphere, passage means communicating the second of said compartments with the intake manifold, spring means urging said plunger into a minimum restriction position and said second compartment to maximum volume, check valve means permitting relatively unrestricted collapse of said second compartment and closing of said first-mentioned valve means in response to a decrease in pressure differential between the intake manifold and the atmosphere, said check valve means having a pressure decay means permitting a controlled and restricted expansion of said second compartment over a predetermined period in response to an increase in pressure differential between the intake manifold and the atmosphere. 